A secondary battery (rechargeable battery) is used as a power supply in electric automobiles or mobile apparatuses such as a smart phone. A lithium-ion secondary battery, for example, is known as one of these secondary batteries.
When a secondary battery is charged, in order to prevent the occurrence of an accident or the shortening of battery life, measures are adopted to prevent overcharging (see Patent Literature 1).
A charging method for a lithium-ion secondary battery described in Patent Literature 1 is a method of charging a battery, which is a lithium-ion secondary battery, while comparing with a protection voltage (Vp) that varies with temperature, and of stopping charging when the battery voltage exceeds the protection voltage (Vp) and switching charging voltage (Vc) according to temperature zone to perform charging, wherein charging is started initially with the highest charging voltage (Vc), battery temperature and voltage are detected, charging is stopped when the battery voltage exceeds the protection voltage (Vp) of the temperature zone detected from the battery temperature, and when the charging is stopped and the voltage drops, constant voltage/constant current charging is performed at a charging voltage (Vc) corresponding to the battery temperature.
PTL 1:
    Japanese Patent Kokai Publication No. JP2009-22079A